<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>DOM CSS</title>
</head>
<body>
<h1 id="demo">使用事件</h1>
<button type="button" onclick="document.getElementById('demo').style.color = 'red'">
  点击
</button>
</body>
</html>